Chicken: Arsenic and antibiotics

July 2007

Chickens eat mostly a corn-and-soy mix, plus rendered animal by-products. Since chickens do not appear to contract mad cow disease, the main issue with their feed is drugs that are intentionally added to kill microbes and fatten birds faster.

Conventional poultry farmers often give chickens Roxarsone (3-Nitro), one of many drugs approved by the Food and Drug Admistration for those purposes. Roxarsone contains arsenic, though in a form less toxic to humans than the form linked to cancer.

The USDA monitors arsenic levels in food animals. Agency researchers ruffled feathers in January 2004 when they reported in Environmental Health Perspectives that young chickens contain three to four times more arsenic than other poultry and meat.

The data were based on analysis of chicken livers. Consumer Reports decided to test both liver and muscle, the part most people eat. We took 116 samples from widely sold brands of conventional and organic chickens bought in stores around the U.S. and from a mail-order company.

We found no detectable arsenic in the 15 liver samples from Foster Farms, a conventional chicken brand, and none in the organic chicken samples. The rest averaged 466 parts per billion (ppb) of total arsenic. That’s still far less than the FDA’s 2,000 ppb chicken-liver tolerance limit–the amount allowed in a food product.

There was no way to tell whether the arsenic came from drugs or was taken up from the environment, where it’s found naturally. But the lack of arsenic in organic chickens is suggestive: USDA standards do not allow arsenic in organic-chicken feed.

The FDA’s tolerance limit for arsenic in chicken muscle meat is 500 ppb–lower than in liver, the FDA says, because people eat more muscle than liver. We found no detectable arsenic in our samples of muscle.

The U.S. Environmental Protection Agency, which regulates arsenic levels in drinking water, has more stringent limits than the FDA. A few of our chicken-liver samples had an amount that according to EPA standards could cause neurological problems in a child who ate 2 ounces of cooked liver per week or in an adult who ate 5.5 ounces per week.

Critics ask why arsenic is allowed in feed at all. “We’re trying to do everything we can to get levels lower in drinking water at very great cost,” Ellen Silbergeld, Ph.D., professor of environmental health sciences at the Johns Hopkins University’s Bloomberg School of Public Health, told us. “And yet we’re deliberately adding it to chicken.”

Asked to comment on the use of arsenic-containing drugs, Richard Lobb, a spokesman for the National Chicken Council, said, “There simply does not appear to be a human health problem of any kind resulting from the use of arsenicals in poultry production.”

Like Roxarsone, human antibiotics are fed to chickens to speed growth. But bacteria in the birds’ intestines can develop resistance to them. People who eat chicken harboring those bacteria can fall ill if they don’t handle and cook meat properly, and they may not be cured by the drugs typically used to get rid of their illness.

In October 2000, the FDA concluded that two antibiotics used in poultry had spawned drug resistance. The maker of one drug pulled it off the market quickly. Bayer, maker of the other drug, challenged the FDA’s proposal to withdraw approval of its drug, Baytril, for use in poultry. In March 2004 an FDA administrative law judge ruled in the agency’s favor. Bayer appealed, and as of November 2004, the FDA had not acted.

On Capitol Hill, proposed legislation would phase out the “nontherapeutic” use in feed of antibiotics important for humans. More than 300 organizations, including the American Medical Association, have endorsed the bill, but its future is uncertain.